PCQLinux 2008 Core was built from scratch to have a minimal installer and installed footprint so as to be a powerful host system for running virtual appliances that we've provided. However, you can also use Core as a fully capable workstation as well. Although the system comes with a basic set of applications; you might want to add a number of others on top of it as well. There are many ways you can do this.

Tech Primer
This distribution is based on CentOS 5.1. Therefore it shares the same installer technology as the original-which is the RPM format. RPM stands for RedHat Package Manager after the creators of this packaging method.
Using RPMs has an advantage over the normal way of installing apps on Linux-that of downloading and compil¬ing source code to get the binary applica¬tion. RPMs have all the required files pre-compiled and all it requires to do is place them in the correct location.

One major issue with using RPMs how¬ever is that of dependencies. Many RPMs depend on other RPMs for certain func¬tionality. If they do not find those RPMs, you need to install them first before in¬stalling the app you want. In case those RPMs further depend on more RPMs, you again need to find and install them even earlier. This can sometimes lead to a long drawn process where a user will need to track down a large number of dependen¬cies and sub-dependencies to many levels before his application can get installed.

Add/remove programs
In case you are running the graphical in¬terface, you can very easily use the Add/Remove Program applet available in the Applications menu on the screen. When you click on this applet (see screen¬shots on next page), it will get a list of ap¬plications installed on your system as well as a number of applications that are avail¬able on the Internet. Obviously, for this to work, your system must be connected to the Internet.

When you get a list of applications, these are categorized under different groups. For instance, you will have appli¬cations under groups like Productivity, Games, System Tools, Development, etc. Browse to the group you wish. You will then see a list of applications that are avail¬able under this group. Ones that are al¬ready installed will have a tick mark next to them while the others can be down¬loaded and installed. Simply select the one that you wish to install.

The great part about the Add/Remove Programs applet is that it automatically re¬solves all dependencies of the main appli¬cation you selected. Which means that you do not need to spend time tracking down other elusive RPMs to get your ap¬plication installed. The applet even lets you review the list of dependencies it finds. Once the applet downloads all the required RPMs, the installation process starts and the RPMs are installed in the or¬der of dependency. When the installation is completed, you are informed about the status and then you can start using the ap¬plication immediately,

Using Yum installer
Yum is the command line version of the software in¬staller and has a number of other options as well. You can down load new applications from a variety of places on the Internet. We have already provided you with a huge number of repositories out of the box in PC¬QLinux 2008. To install a new application, you need to simply give the command: yum install ",application name>
For instance, if you want to install The Gimp, you will give the command: yum In tall qimp.

This will download the headers from all the repos¬itories and calculate the dependencies and inform you. You can then choose to continue with the instal¬lation or not. You can also update an already installed application to the latest version by giving the follow¬ing command: yum update "'application Ilame>
For instance: yum update glmp.

If you wish to remove an application and its de¬pendencies (as long as that dependency is not also used by any other installed application), you can give the command: yUill remove ",application name>
If you want to add more repositories to the list of places where you can download applications from, go to / etc/yum.repos.d and create a new file with the ex¬tension of .repo having the following format: [<Repository Name>]
name=<Friendly Name>
mirrorlist=<URL of mirrors>
Itbaseurl=<U RL of base>
gpgcheck=<O or 1>
enabled=l
gpgkey=<URL to GPG file>
In this, you can use either the mirrorlist or the baseurl value. You can also choose whether to do a GPG check on the downloaded RPMs or not. For in¬stance, the following adds the Livna repository to the system:
[livna]
nalne=Livna for PCQLinux 2008 mirrorlist/mirrorlist-7 enabled=l
gpgcheck=l
gpgkey=http://rpm.livna.orgjrpm gpg/RPM GPG KEY livna You can now use this repository to download files as well.
Installing with RPM
As a final resort, if you cannot do an automatic down¬load and install of your application (as it is not avail¬able in a repository), you can download RPMs if they are available and install them manually. For this you can either double click the RPM file in the File Ex¬plorer or open a terminal window and enter the follow¬ing command: rpm -ivh <RPM filename>
For instance, to install the Open Office RPMs given on the PCQLinux 2008 Appliances DVD, mount the DVD, browse to the OpenOffice directory and give the following command: rpm -ivh '.rpm.

Within a given set of RPMs, the rpm command can also find the dependencies and install them in the cor¬rect order. However, if it does not find a file that re¬solves a dependency, it will fail and exit. In which case you will need to track down the correct RPM and in¬stall it yourself.